Her first marriage to Neil Zarach, a designer, ended in divorce. In 2003, she married the President of Iceland, Ólafur Ragnar Grímsson, on his birthday, 14 May 2003, following an engagement of three years.[3]

Moussaieff describes herself as "religious in the soul,"[4] and continues to observe Jewish rituals, such as lighting Hanukkah candles.[5]

As a child, Moussaieff spent a lot of time in her family's jewellery store on Hilton Park Lane in London, and went on to become a successful jewellery designer.[1] Other business ventures in which she has been involved are the construction of an office building at Canary Wharf, London and a tourism project in Turkish Cyprus.[1] Moussaieff is a contributing editor to the British society magazine Tatler.

In 2003, Moussaieff married Ólafur Ragnar Grímsson, President of Iceland, on his 60th birthday. She has helped present Icelandic culture abroad, promoted Icelandic artists and identified foreign markets for Icelandic products. She is also active in raising money for disabled children.[6]

In May 2006, while visiting Israel, Moussaieff was detained at Ben Gurion International Airport after arguing with security personnel who refused to acknowledge her British passport and told her that she was obliged by Israeli law to enter and exit the country using an Israeli passport. The media related the confrontation as a diplomatic incident.[7] The Israeli Embassy in Norway, which handles diplomatic relations with Iceland, expressed regret over the incident and restated the law that Israeli citizens must carry Israeli passports when in the country.[8]

Moussaieff was listed third on the Harper's Magazine List of the Most Connected People in Britain.[1] A local magazine in Reykjavík chose her as one of the best-dressed women in Iceland.[9] Moussaieff was also named Woman of 2006 by the popular Icelandic glossy magazine Nýtt Líf.[10]